Abstract Excavated soils and rocks, containing toxic metals and/or metalloids from geogenic sources, are usually generated in huge volumes at construction sites. And the post-excavation leaching of these toxic metals and/or metalloids with low concentrations, but higher than the environmental standards, is a major environmental concern. A sorption layer method was developed as a cost-effective countermeasure for treating and reusing such excavated soils and rocks. The method utilizes a permeable soil layer, with sorption capacity at the bottom of the embankment, to retain the chemicals of concern that have dissolved in the leachate. Clean host soil, amended with toxic metal-immobilizing agents, is often used as the sorption layer material to strengthen the sorption performance. This study examined the feasibility of applying decomposed granite soil, amended with calcium-magnesium (Ca-Mg) composite powder, as the sorption layer material against the natural contamination of arsenic (As). The hydraulic and sorption performances, along with the effect of the mix proportions and curing periods, were evaluated through batch sorption tests, hydraulic conductivity tests, and up-flow column percolation tests. The results showed that the sorption performance increased by 15 times when using an additive content of 5% Ca-Mg and that hydraulic conductivity was maintained at around 1 × 10−6 m/s. Neither the hydraulic nor the sorption performance was strongly affected by curing periods up to 28 days. The sorption performance increased with the addition of the Ca-Mg agent of up to 5% in the batch sorption tests. The permeable hydraulic property, with an improved sorption capacity due to the soil-agent mixture, indicated that it is a promising material for use with the sorption layer method for treating huge amounts of soils with low levels of contamination.

中文翻译：

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钙镁复合粉改性土壤对天然砷污染的水力和吸附性能

摘要 挖掘出的土壤和岩石含有来自地质来源的有毒金属和/或准金属，通常在建筑工地大量产生。并且这些有毒金属和/或类金属的开挖后浸出浓度低但高于环境标准，是一个主要的环境问题。吸附层法被开发作为处理和再利用此类挖掘出的土壤和岩石的经济有效的对策。该方法利用在路堤底部具有吸附能力的可渗透土壤层来保留已溶解在渗滤液中的相关化学物质。用有毒金属固定剂修饰的清洁宿主土壤通常用作吸附层材料以增强吸附性能。本研究考察了使用钙镁（Ca-Mg）复合粉末改性的分解花岗岩土壤作为吸附层材料以抵抗砷（As）的自然污染的可行性。水力和吸附性能，以及混合比例和固化时间的影响，通过批量吸附测试、水力传导率测试和上流柱渗透测试进行评估。结果表明，当使用 5% Ca-Mg 添加剂时，吸附性能提高了 15 倍，并且水力传导率保持在 1 × 10-6 m/s 左右。长达 28 天的固化时间对水力性能和吸附性能都没有强烈影响。在批量吸附测试中，吸附性能随着添加高达 5% 的 Ca-Mg 剂而提高。